1. Field of the Invention
The present invention relates to a power supply control device for a camera, and more particularly pertains to a power supply control circuit for a camera provided with two electronic flash devices. One flash device is for the illumination of a scene to be photographed and the other is for the illumination of data to be recorded, with both electronic flash devices being supplied with electric energy from a common power source.
2. Description of the Prior Art
Devices are well known which, upon exposure of a film to photograph an object scene, records auxiliary information on the film, such as numerals for identifying the photography, or the exposure conditions used for taking the picture, or other data relating to the picture being taken. It has been common for such information recording devices, or data recording or imprinting devices, that an illuminating lamp such as a tungsten lamp is lit for a given time interval in conjunction with the picture taking operation of the camera, in order to project an image of the information to be recorded on the film. Such a tungsten lamp should be lit for a duration of approximately 0.5 seconds. It has been customary to actuate a monostable multivibrator in response to an exposure termination signal from an exposure time control circuit to light the lamp for the given duration of time. During the time the lamp is maintained lit, an electric power source must be connected to the circuit for lighting the lamp. In the case where a switch for the power supply is adapted to open and close in conjunction with the movement of a shutter release button, some measure has to be taken such that the current supply to the lamp is maintained for a duration of time, even if the shutter release button is released to assume its initial position immediately after it has been operated.
Cameras are known, in which an electronic flash device is incorporated and a power source for the electronic flash is also used in common for the data recording lamp. With such a camera, immediately after the electronic flash lamp is fired, a main capacitor for storing energy for energizing the flash lamp beings to be recharged which greatly decreases the voltage of the source battery from its normal level, resulting in failure to energize and light the data recording lamp for the duration of time required. To avoid this, one of the prior art power supply control circuits for the electronic flash and the data recording lamp, was arranged to temporarily interrupt the operation of the oscillator circuit for producing high voltage to be applied to the main capacitor for the duration that the data recording lamp was being lit.